Xylem 51-S-2 McDonnell & Miller Mechanical Water Feeder with Low Water Cut-Off

The McDonnell & Miller 51-S-2 is a combination float-operated mechanical water feeder and low water cut-off (LWCO) designed for low pressure steam and hot water boilers with capacities up to 35,000 square feet. This reliable boiler control device automatically maintains minimum safe water levels while providing critical low water cut-off protection.

Key Features:

• Proportional feed action for precise water level control
• Equipped with No. 2 switch for automatic low water cut-off function
• Float block design with automatic reset capability
• 1" FIP screwed connection for easy installation
• Continuous water level maintenance independent of electrical service
• Maximum water supply pressure: 100 PSI (7 kg/cm²)
• Maximum inlet water temperature: 120°F (49°C)
• Maximum vessel pressure: 35 PSI (2.5 kg/cm²)

The 51-S-2 provides essential protection for commercial and industrial boiler systems by automatically feeding water when levels drop and shutting down the boiler if water levels become dangerously low. This dual-function design ensures both operational efficiency and critical safety protection for your boiler investment.